The present invention relates to dielectric barrier discharge lamps. In particular, the present invention relates to dielectric barrier discharge lamps for use in fluid treatment systems, luminary systems and other applications.
Dielectric barrier discharge lamps are generally known and are used in a variety of applications where electromagnetic radiation of a particular wavelength is desired. For example, some applications include wastewater treatment and/or the disinfection of drinking water. These applications can require ultraviolet radiation with wavelengths between about 100 nm and 280 nm. Other applications include generating visible light for general lighting, which can require wavelengths between about 380 nm and 750 nm.
Dielectric barrier discharge lamps can generally be of any form. One of the simplest forms of dielectric barrier discharge lamps includes an outer tube and a coaxial inner tube forming an annular discharge chamber therebetween. An electrode within the inner tube and a counter-electrode about the exterior of the outer tube are spaced apart by the annular discharge chamber. The chamber normally includes a noble or rare gas, such as xenon, which emits a primary radiation as soon as a gas discharge, especially a dielectric barrier discharge, is initiated inside the discharge chamber. During dielectric barrier discharge, xenon molecules disassociate into ions and electrons and become xenon plasma. When the xenon plasma is excited to a specific energy level, eximer molecules are formed within the plasma. The eximer molecules divide after a certain lifespan, releasing photons having a peak wavelength of about 172 nm for xenon plasma. This energy can be converted to a range of 175 nm-280 nm through a luminescent layer deposited on the interior of the outer tube. At least the outer tube can be formed of a translucent material, such as quartz, to transmit ultraviolet radiation for the disinfection of water or air, or for other applications.
Prior art systems can also include a step-up transformer wound about a common magnetic core for converting a mains or first voltage into a second voltage for application across the electrode and the counter-electrode. However, the step-up transformer must normally include physical connections to a power supply and the lamp body. In use, the connection (e.g., electrical contacts) between the transformer and the lamp body can be susceptible to fluid and corrosion. In addition, a major obstacle to the efficient treatment of fluid by prior art dielectric barrier gas discharge lamps is the irradiation of the fluid at levels above or below the level needed for adequate treatment.